U.S. officials say they are seeking a 28-year-old man in connection with the September 17 blast in New York.

Local police released on September 19 a photograph of a naturalized U.S. citizen of Afghan origin identified as Ahmad Khan Rahami.

Mayor Bill de Blasio said the man could be armed and dangerous.

The explosion of a homemade bomb in Manhattan’s Chelsea area injured 29 people.

Federal investigators said tests revealed the bomb contained residue of Tannerite, an explosive often used for target practice that can be obtained from sporting-goods stores.

Authorities are still investigating whether the blast was connected to an unexploded pressure-cooker device found just blocks away, a pipe-bomb blast at a Jersey shore town, and explosive devices found in a bag at a New Jersey train station.

U.S. officials say one of the suspicious devices found near the New Jersey train station exploded early on September 19 as a bomb squad was attempting to disarm it with a robot.

Elizabeth Mayor Christian Bollwage said bomb experts were working to disarm one of up to five devices found in a bag in a wastebasket near the train station.

There was no immediate report of injuries.

An image of Ahmad Khan Rahami, who is wanted for questioning in connection with an explosion in New York City, is seen in a a poster released by the Federal Bureau of Investigation (FBI) on September 19, 2016

U.S. media reports say five people were taken into custody for questioning late on September 18 in connection with the Manhattan bombing.

Reports said the five were detained together in a car that was stopped on a highway in New York's Brooklyn borough and were taken to an FBI building in Manhattan for questioning.

The FBI said early on September 19 that none of the five had been charged in connection with the explosion in Chelsea.

In New Jersey, meanwhile, a pipe bomb exploded and forced the cancellation of a military charity race.

Officials said there was no initial evidence linking either attack to any international terrorist group.